Carbonate - Declaration

Properties of carbonates

Carbonates are divalent salts of carbonic acid. The carbonic acid H 2 CO 3 has two series of salts: The hydrogen carbonates with the anion HCO 3- and the carbonates with the anion CO 32 -.

In Karbonatanion three oxygen atoms are bonded to a carbon atom. The ion is completely planar and all the OCO angle is 120 °.

Carbonates are crystalline, odorless solids at room temperature in the rule. Their color is determined by the cation of the salt.

Carbonates react as a base by accepting a proton and Hydrogenkarbonation HCO 3- react. When heated they decompose into a metal oxide and carbon dioxide, such as calcium carbonate: CaCO3 -> CaO + CO 2.

Qualitative detection of carbonates is done with barium hydroxide solution in a fermentation tube. The sample solution is acidified with hydrochloric acid and sealed with a Gährröhrchen. Are carbonates, they react with the acid to CO 2: CO 32 - + 2HCl -> CO 2 + 2Cl - + H 2 O. The CO 2 rises to the top and is passed through the fermentation tube in the barium hydroxide solution. In the following reaction, the sparingly soluble barium carbonate precipitates as a white precipitate: CO 2 + Ba (OH) 2 -> BaCO 3 + H 2 O.

Use of carbonates

Calciukarbonat CaCO 3 (limestone) is mainly used in the construction industry and as fertilizer.

Magnesium is used by athletes to increase the grip, z. B. in gymnastics, weightlifting and pole vault.

Various carbonates, such as those of sodium, barium, manganese and potassium used as food additives, for the manufacture of glass, as fertilizer, or raw materials in the chemical industry.